The aircraft passenger seats are required to stay attached to a floor of the aircraft or not deform greatly even in a state where an acceleration of 16 times the gravity of the earth is applied when the aircraft makes a belly landing. This request can be proved through a movement load test that applies an acceleration of 16 times the gravity to the seat.
In a prior art product, the whole body of the seat is bent to absorb the impact of the test by methods such as reducing a plate thickness of the respective members, but such methods lead to the drawback of causing passengers to feel unsafe by the bending of the seat during use, or to distortion of the structural members leading to deterioration of movement of movement members.
In general, metal may easily be damaged where a force is added in a state where bend or torsion exists compared to a state where the bend or torsion exists. If the seat adopts a configuration where displacement or the load applied during the test is conducted to a plurality of components in the state of bend or torsion, the respective components must be reinforced, which leads to the increase of the weight of the whole seat.
In the aircraft seat, the required load is extremely great, but on the other hand, the weight must be reduced to suppress the operation cost of the airframe, so that unnecessary reinforcement must be avoided by preventing bend or torsion from occurring in multiple components through structural design.